1. Field of the Invention
The present invention relates to an apparatus and a method for evaluation of vegetables and fruits which enable optically and nondestructively evaluating (measuring) the interior quality, such as sweetness degree (sugar content), acidity and maturity grade (ripening degree), of vegetables and fruits with the use of a carrier line.
2. Description of the Prior Art
Various techniques for measuring the interior quality, such as degree of sweetness (sugar content), acidity and maturity grade (ripening degree), of vegetables and fruits from the exterior without destroying them have been proposed.
As for the methods for nondestructively measuring the interior quality of vegetables and fruits, vegetables and fruits are irradiated with near infrared rays. In particular, the method of using reflection and the method of using a transmitted light have been proposed.
The method of using a reflected light is suitable to the measurement of, for example, peaches, pears and apples having a relatively thin epidermis. In this method, a measuring light (measuring beam), which has been transmitted through a thin epidermis, is reflected on a surface layer portion of sarcocarp, received by a light-receiving section. Then, the measuring light is analyzed so that measuring and evaluation of the interior quality of the above items can be achieved. However, in this method of using a reflected light, there is a drawback in that the light reflected on the vicinity of the surface layer portion or sarcocarp is received, so that only the interior quality of the vicinity of the epidermis can be identified by the analysis of obtained reflected light.
On the other hand, the evaluation method of using a transmitted light is suitable to the measurement of, for example, citrus fruits such as tangerines and oranges, melons and watermelons having a relatively thick epidermis. In this method, an irradiated measuring light is transmitted through the interior of sarcocarp and exits from the opposite side. Then, the irradiated measuring light is received by a light-receiving section and analyzed so that measuring and evaluation of the interior quality of the above items can be achieved. In this method of using a transmitted light, there is advantage that the light having been transmitted through the interior of sarcocarp of vegetables and fruits is analyzed, so that the properties of sarcocarp can be evaluated more accurately than in the method of using a reflected light. Therefore, the method of using a transmitted light is increasingly employed (see, for example, Japanese Registered Utility Model Publication No. 3049026 and Japanese Patent Laid-open Publication No. 2002-139442).
Evaluation apparatus 100 of single transmitted light type for vegetables and fruits, as shown in FIGS. 22 and 23, is heretofore in use as an evaluation apparatus of transmitted light type wherein a transmitted light is utilized as mentioned above.
Specifically, in this evaluation apparatus 100 for vegetables and fruits, light source 104 is disposed by one side of carrier line 102, such as a conveyor, in width direction Y perpendicular to carrying direction X of the carrier line 102. Further, light-receiving section 106 is disposed by the other side of the carrier line 102 in the width direction Y perpendicular to the carrying direction X of the carrier line 102. Thus, in this apparatus, a measuring light irradiated from the light source 104 is transmitted through the interior of sarcocarp of each of vegetables and fruits 108, and exits from the opposite side. Then, the measuring light is received by the light-receiving section 106 and is analyzed by a separate analyzer (not shown), so that measuring and evaluation of the interior quality of vegetables and fruits 108 can be achieved.
However, the above evaluation apparatus 100 for vegetables and fruits wherein a single light source 104 is disposed is in exclusive use, for example, for watermelons, or for tangerines. When, for example, tangerines having relatively small size, and small thickness of sarcocarp and pericarp (skin) are measured on a line for use in the measurement of, for example, watermelons having relatively large size, and large thickness of sarcocarp and pericarp, the quantity of light to be irradiated and the quantity of light to be received are too large so that accurate measurements cannot be expected. On the other hand, when contrarily watermelons are measured on a line for use in the measurement of tangerines, the light quantities are too small so that accurate measurements cannot be expected. That is, too large or too small light quantities cause the measurements to be inaccurate. Therefore, even when, for example, the watermelon line is free in the winter, it has been difficult to use the line for measurement of tangerines.
Moreover, only a diversion between watermelons and tangerines whose harvesting seasons are different could be coped with by purchasing two evaluation apparatuses and carrying out replacement of apparatuses in appropriate seasons. However, in the case of items whose harvesting seasons overlap, frequent replacements would be inevitable. Furthermore, when a variety of items are to be measured on a single line, the same number of evaluation apparatuses must be provided so that an enormous cost is incurred and further necessitates endeavoring to acquire storage sites.
Accordingly, as shown in FIGS. 24 and 25, evaluation apparatus of passing light type 200 for vegetables and fruits wherein a plurality of light sources are disposed in a horizontal direction so as to enable evaluation of vegetables and fruits having large size, and large thickness of sarcocarp and pericarp has been proposed.
In this evaluation apparatus 200 for vegetables and fruits, a plurality of horizontally arranged light sources 204a to 204e are disposed by one side of carrier line 202 in width direction Y perpendicular to carrying direction X of the carrier line 202. Further, light-receiving section 206 is disposed by the other side of the carrier line 202 in the width direction Y perpendicular to the carrying direction x of the carrier line 202. Thus, in this apparatus, as indicated by alternate long and two short dashes lines in FIG. 25, measuring lights irradiated from the light sources 204a to 204e are transmitted through the interior of sarcocarp of each of vegetables and fruits 208 and exits from the opposite side. Then, the measuring light is received by the light-receiving section 206 and is analyzed by a separate analyzer (not shown) so that measuring and evaluation of the interior quality of vegetables and fruits 208 can be achieved.
In the evaluation apparatus 200 for vegetables and fruits, a plurality of light sources 204a to 204e are employed as different from the aforementioned evaluation apparatus of single transmitted light type 100 for vegetables and fruits. Therefore, the evaluation apparatus 200 for vegetables and fruits enables increasing the number of transmitted lights, so that vegetables and fruits having relatively large size, and large thickness of sarcocarp and pericarp can be treated.
However, in this evaluation apparatus 200 for vegetables and fruits, vegetables and fruits 208 are moved on the carrier line 202 even during the measurement thereof, and a plurality of light sources 204a to 204e are arranged in a horizontal direction. Therefore, during the measurement of vegetables and fruits 208 being moved on the carrier line 202, especially at the beginning or ending of measurement, it has unfavorably occurred that the light-receiving section 206 receives lights from the periphery of vegetables and fruits 208 other than the intended transmitted lights, such as straight lights from the peripherally arranged light sources, for example, light sources 204a to 204e, reflected lights from vegetables and fruits 208 and reflected lights from neighboring vegetables and fruits 208. As a result, the accuracy of measuring evaluation is deteriorated.
This phenomenon can be avoided by shortening the measuring time. However, generally, the accuracy of measuring evaluation would be deteriorated by shortening of the measuring time.
With respect to the evaluation apparatus of single transmitted light type 100 for vegetables and fruits, single light source 104 is used, so that this phenomenon is relatively slight. However, receiving of such lights other than the intended transmitted light cannot be fully avoided.
Furthermore, in the evaluation apparatus 200 for vegetables and fruits, although vegetables and fruits having relatively large size, and large thickness of sarcocarp and pericarp thickness can be treated, accurate measuring of vegetables and fruits having relatively small size and small thickness of sarcocarp and pericarp cannot be realized because the quantity of light to be irradiated and the quantity of light to be received are too intense.
Under these circumstances, it is an object of the present invention to provide an evaluation apparatus for vegetables and fruits and an evaluation method for vegetables and fruits which, in the measuring of vegetables and fruits being moved on a carrier line, enable realizing accurate measuring evaluation with strikingly enhanced precision while avoiding the receiving, by a light-receiving section, of lights from the periphery of vegetables and fruits other than intended transmitted lights, such as straight lights from light sources, reflected lights from vegetables and fruits and reflected lights from neighboring vegetables and fruits.
It is another object of the present invention to provide an evaluation apparatus for vegetables and fruits and an evaluation method for vegetables and fruits which enable realizing accurate measuring evaluation with strikingly enhanced precision with respect to vegetables and fruits having widely varied size and varied thickness of sarcocarp and pericarp as well.